Roughness measurement of oriented surface by depolarization of scattered light

• Published in: Optics and lasers in engineering 2019-01, Vol.112, p.87-92
• Main Authors: Camargo, A.L.P., Fellows, C.E., Lemos, M.R., Mello, M.M., da Silva, L., Huguenin, J.A.O.
• Format: Article
• Language: English
• Subjects: Depolarization; Roughness; Scattering
• ISSN: 0143-8166; 1873-0302
• DOI: 10.1016/j.optlaseng.2018.09.004

•Cross-polarization ratio (CPR) analysis for laser light depolarization by scattering in rough surfaces were successfully applied for oriented rough surface, typical finishing in industrial lines.•An clear dependence of depolarized laser light intensity by respect the surfaces mean roughness (Ra) was observed for two different mean roughness range.•The direct dependence of the depolarized light intensity by respect Ra is a proof of principle for application in indirect measurement of roughness. The access by inversion of a single light intensity measurement open the possibility to construct a fast method to control metallic surface roughness with potential application in industrial production lines. In this work we present a study of light depolarization by an oriented rough surface. A polarized laser beam shines samples with different roughness in two different ranges and the intensity of depolarized light at normal direction is monitored. We show the applicability of Cross–Polarization Ratio (CPR) analysis, previously applied to random rough surfaces, for oriented rough surface. In addition, we observed a clear dependence of the depolarized light intensity by respect the sample’s mean roughness (Ra) for both analyzed roughness range. Our results consist in a proof of principle for indirect roughness measurement of metallic samples and intend to be a potential application in industrial production line, once Ra can be related directly with an intensity measurement in a fast way.